The net value to society is likely negative since the impact on the target is large, and a society that allowed such things may see time horizons constrict.

You raise some good points, though. I personally am probably coming with an unspoken understanding that 'given that something fits into a legal and moral structure, and we accept a certain definition of using something by choice as value' then paying more for that thing implies more value. Facebook is probably a good example of something in the grey area, connecting people has value, but generating demand is questionable, spreading misinformation is likely a large net negative.